MEMS resonator array structure

ABSTRACT

A MEMS array structure includes MEMS resonators that form an array. Each MEMS resonator includes beam sections. At least one of the beam sections of a first one of the MEMS resonators is a shared beam section that is also included in another of the MEMS resonators adjacent to the first MEMS resonator.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of and claims priority under 35U.S.C. § 120 to U.S. application Ser. No. 11/172,143 filed Jun. 30,2005, now U.S. Pat. No. 7,227,432, the entirety of which is incorporatedherein by reference in its entirety.

BACKGROUND

This invention relates to a microelectromechanical ornanoelectromechanical resonator array structure, and method ofdesigning, operating, controlling and/or using such an architecture; andmore particularly, in one aspect, to a plurality ofmicroelectromechanical or nanoelectromechanical resonators (for example,a plurality of resonators at least one of which includes one or moreenhanced nodal points that facilitate substrate anchoring in order tominimize influence of packaging stress and/or energy loss via substrateanchoring) that are mechanically coupled to provide one or more outputsignals having one or more frequencies.

Generally, high Q microelectromechanical resonators are regarded as apromising choice for integrated single chip frequency references andfilter. In this regard, high Q microelectromechanical resonators tend toprovide high frequency outputs that are suitable for many high frequencyapplications requiring compact and/or demanding space constraineddesigns. However, while the resonator is being scaled smaller, packagingstress, energy loss into the substrate through substrate anchors,reduced signal strength, and/or instability or movement of the center ofgravity during oscillation tend to adversely impact the frequencystability as well as “Q” of the resonator.

There are several well-known resonator architectures. For example, onegroup of conventional resonator architectures employs closed-ended oropen-ended tuning fork. For example, with reference to FIG. 1,closed-ended or double-clamped tuning fork resonator 10 includes beamsor tines 12 a and 12 b. The beams 12 a and 12 b are anchored tosubstrate 14 via anchors 16 a and 16 b. The fixed electrodes 18 a and 18b are employed to induce a force to beams 12 a and 12 b to cause thebeams to oscillate (in-plane).

The characteristics and response of tuning fork resonator 10 are wellknown. However, such resonator architectures are often susceptible tochanges in mechanical frequency of resonator 10 by inducing strain intoresonator beams 12 a and 12 b as a result of packaging stress. Inaddition, conventional resonator architectures, like that illustrated inFIG. 1, experience or exhibit energy loss, though the anchors, into thesubstrate.

Certain architectures and techniques have been described to addressQ-limiting loss mechanism of energy loss into the substrate throughanchors as well as changes in frequency due to certain stresses. In oneembodiment, the beams of the resonator may be “suspended” above theground plane and sense electrode whereby the vibration mode of the beamis out-of-plane. (See, for example, U.S. Pat. No. 6,249,073). While sucharchitectures may alleviate energy loss through the anchors, resonatorsthat include an out-of-plane vibration mode (i.e., transverse mode) tendto exhibit relatively large parasitic capacitance between drive/senseelectrodes and the substrate. Such capacitance may lead to a highernoise floor of the output signal (in certain designs).

Other techniques designed to improve the Q-factor of the resonator havebeen proposed and include designing the spacing between the vibratingbeams so that such beams are closely spaced relative to a wavelengthassociated with their vibrating frequency. (See, for example, thesingle-ended or single-clamped resonator of U.S. Pat. No. 6,624,726).The vibrating beams are driven to vibrate one-half of a vibration periodout of phase with each other (i.e., to mirror each others motion). Whilethese architectures and techniques to improve the Q of the resonator maysuppress acoustic energy leakage, such an architecture remainpredisposed to packaging stress, energy loss into the substrate throughsubstrate anchors as well as a “moving” of the center of gravity of theresonator during motion by the vibrating beams of the single-ended orsingle-clamped resonator.

Further, other resonator architectures have been described to addressenergy loss through the anchor, for example, a “disk” shaped resonatordesign. (See, for example, U.S. Patent Application Publication2004/0207492). Indeed, an array of identical mechanically-coupleddisk-shaped resonators has been proposed to decrease motional resistancewhile improving linearity. (See, for example, U.S. Pat. No. 6,628,177and “Mechanically Corner-Coupled Square Microresonator Array for ReducedSeries Motional Resistance”, Demirci et al., Transducers 2003, pp.955-958).

There is a need for a resonator array architecture, configuration orstructure that overcomes the shortcomings of one, some or all of theconventional architectures, configurations or structures. In thisregard, there is a need for improved array of microelectromechanicaland/or nanoelectromechanical resonators having improved packaging stresscharacteristics, reduced and/or minimal energy loss into the substratethough substrate anchors, and/or improved or optimal stability of thecenter of gravity during oscillation. In this way, the signal to noiseof the output signal is increased, the stability and/or linearity of theoutput frequency of the resonator is enhanced, and/or the “Q” factor ofthe resonator is relatively high.

Further, there is a need for an improved microelectromechanicalresonator array architecture, configuration or structure that includesrelatively small motional resistance and good linearity, implements fulldifferential signaling and/or possesses a high immunity to on the inputsignals and/or the output signals. Moreover, there is a need for animproved method of designing, operating, controlling and/or using such aresonator array that overcomes the shortcomings of one, some or all ofthe conventional resonator array architectures, configurations orstructures.

SUMMARY OF THE INVENTION

There are many inventions described and illustrated herein, as well asmany aspects and embodiments of those inventions. This Summary discussessome of the inventions described and claimed herein. By no means is thisSummary of the Invention is not exhaustive of the scope of the presentinventions. With that in mind, in a first principal aspect, the presentinvention is a MEMS array structure comprising a plurality of MEMSresonators coupled via one or more resonator coupling sections. In oneembodiment, each MEMS resonator includes a plurality of elongatedstraight beam sections (for example, four elongated straight beamsections), each including first and second ends, and a plurality ofcurved sections (for example, four curved sections), each includingfirst and second ends, wherein each end of a beam section is connectedto an associated end of one of the curved section to thereby form ageometric shape (for example, a rounded square shape).

In one embodiment, the MEMS array structure may further include at leastone resonator coupling section which is disposed between each of theopposing elongated straight beam sections of adjacent MEMS resonators.

In addition, in one embodiment, at least one curved section of at leastone MEMS resonator may include a nodal point wherein the MEMS arraystructure further includes at least one anchor coupling section and asubstrate anchor, coupled to the nodal point via the anchor couplingsection, to secure the MEMS resonator to a substrate. The MEMS arraystructure may also include a stress/strain relief mechanism disposedwithin the anchor coupling section and between the substrate anchor andthe nodal point.

In another embodiment, at least one curved section of each MEMSresonator includes a nodal point and wherein the MEMS array structurefurther includes at least one anchor coupling section disposed betweenan associated nodal point and a substrate anchor and wherein thesubstrate anchor secures the MEMS resonator to a substrate. Astress/strain relief mechanism maybe disposed within the anchor couplingsection and between the substrate anchor and the nodal point.

In one embodiment, each resonator coupling section includes voids toreduce the mass of the section. In another embodiment, each resonatorcoupling section includes a filleted shape at the ends such that theends of the resonator coupling section have a greater width than themiddle of the resonator coupling section.

Notably, each curved section of each MEMS resonator may include at leastone nodal point. In this embodiment, the at least one nodal point ofeach MEMS resonator is connected to a substrate anchor via an associatedanchor coupling section. The MEMS resonator array structure may includea plurality of stress/strain relief mechanisms disposed within anassociated anchor coupling section and between an associated substrateanchor and an associated nodal point.

In certain embodiment, the plurality of elongated straight beam sectionsof each MEMS resonator includes a plurality of slots disposed therein.Moreover, at least one of the plurality of curved sections of each MEMSresonator includes a plurality of slots disposed therein. Indeed, thewidth of each elongated straight beam section of the MEMS resonator isgreater at the ends than in the center thereof.

In another principal aspect, the present invention is a MEMS arraystructure comprising a plurality of MEMS resonators, a plurality ofresonator coupling sections and a plurality of anchor coupling sections.Each MEMS resonator includes a plurality of elongated straight beamsections and a plurality of curved sections (for example, four elongatedstraight beam sections and four curved sections). Each beam sectionincludes a first end and a second end. Further, each curved sectionincludes a first end and a second end, wherein each end of a beamsection is connected to an associated end of one of the curved sectionto thereby form a geometric shape (for example, a rounded square shape).Moreover, at least one curved section includes a nodal point.

In this aspect, at least one resonator coupling section is disposedbetween at least one pair of opposing elongated straight beam sectionsof adjacent MEMS resonators such that each MEMS resonator is connectedto at least one adjacent MEMS resonator. In addition, the at least onenodal point of each MEMS resonator is connected to a substrate anchorvia an associated anchor coupling section.

In one embodiment, MEMS array structure further includes a plurality ofstress/strain relief mechanisms, wherein at least one stress/strainrelief mechanism is disposed within an associated anchor couplingsection and between the substrate anchor and the nodal point of the MEMSresonator. The resonator coupling sections may include voids to reducethe mass of the section. The resonator coupling sections may, inaddition to or in lieu thereof, include a filleted shape at the endssuch that the ends of the resonator coupling section have a greaterwidth than the middle of the resonator coupling section.

In another embodiment, the plurality of elongated straight beam sectionsof each MEMS resonator includes a plurality of slots disposed therein.Indeed, the plurality of curved sections of each MEMS resonator mayinclude a plurality of slots disposed therein.

The MEMS array structure may also include a plurality of senseelectrodes, a plurality of drive electrodes, and sense circuitry. Thesense and drive electrodes are juxtaposed the plurality of elongatedstraight beam sections of the MEMS resonators. The sense circuitry iscoupled to the sense electrodes to provide an output signal.

The sense electrodes may provide one or more signals to the sensecircuitry which, in response, provides a differential output signal. Thesense electrodes may provide one or more signals to the sense circuitrywhich, in response, provides a single ended output signal.

In another principal aspect, the present invention is a MEMS arraystructure comprising a plurality of MEMS resonators wherein each MEMSresonator includes a plurality of elongated straight beam sections, aplurality of curved sections, wherein each end of a beam section isconnected to an associated end of one of the curved section to therebyform a geometric shape. The MEMS array structure may further include oneor more resonator coupling sections. In this embodiment, each of theopposing elongated straight beam sections of adjacent MEMS resonatorsincludes a resonator coupling section connected therebetween. The MEMSarray structure may also include a plurality of sense electrodes, aplurality of drive electrodes, wherein the sense and drive electrodesare juxtaposed one or more of the plurality of elongated straight beamsections of the MEMS resonators. Sense circuitry, coupled to the senseelectrodes, provides an output signal (for example, a differentialoutput signal and/or a single ended output signal).

In one embodiment, one or more sense electrodes are disposed within thegeometric shape of at least one of the MEMS resonators. Indeed, the oneor more sense electrode may be juxtaposed a plurality of elongatedstraight beam sections of the at least one of the MEMS resonator.

In one embodiment, at least one curved section of at least one of theplurality of MEMS resonators includes a nodal point. In this embodiment,the MEMS array structure further includes at least one anchor couplingsection and a substrate anchor, coupled to the nodal point via theanchor coupling section, to secure the MEMS resonator to a substrate.

The MEMS array structure may include a stress/strain relief mechanismdisposed within the anchor coupling section and between the substrateanchor and the nodal point.

In another embodiment, each curved section of each MEMS resonatorincludes at least one nodal point. In this embodiment, at least onenodal point of each MEMS resonator is connected to a substrate anchorvia an associated anchor coupling section. A plurality of stress/strainrelief mechanisms may be disposed within an associated anchor couplingsection and between an associated substrate anchor and an associatednodal point. The resonator coupling sections may include voids to reducethe mass of the section to a filleted shape at the ends such that theends of the resonator coupling section have a greater width than themiddle of the resonator coupling section.

Again, there are many inventions, and aspects of the inventions,described and illustrated herein. This Summary discusses some of theinventions described and claimed herein. By no means is this Summary ofthe Invention is not exhaustive of the scope of the present inventions.Moreover, this Summary of the Invention is not intended to be limitingof the invention and should not be interpreted in that manner. Whilecertain embodiments have been described and/or outlined in this Summaryof the Invention, it should be understood that the present invention isnot limited to such embodiments, description and/or outline. Indeed,many others embodiments, which may be different from and/or similar to,the embodiments presented in this Summary, will be apparent from thedescription, illustrations and claims, which follow. In addition,although various features, attributes and advantages have been describedin this Summary of the Invention and/or are apparent in light thereof,it should be understood that such features, attributes and advantagesare not required whether in one, some or all of the embodiments of thepresent inventions and, indeed, need not be present in any of theembodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

In the course of the detailed description to follow, reference will bemade to the attached drawings. These drawings show different aspects ofthe present invention and, where appropriate, reference numeralsillustrating like structures, components, materials and/or elements indifferent figures are labeled similarly. It is understood that variouscombinations of the structures, components, materials and/or elements,other than those specifically shown, are contemplated and are within thescope of the present invention.

FIG. 1 is a block diagram (top view) representation of a conventionalmicroelectromechanical tuning fork resonator device;

FIG. 2A is a schematic representation of MEMS resonator array having anN×M MEMS resonator configuration, according to one aspect of the presentinventions, wherein each MEMS resonator of the array is coupled to theadjacent resonator;

FIG. 2B is a schematic representation of MEMS resonator array having anN×M MEMS resonator configuration, according to one aspect of the presentinventions, wherein the MEMS resonators of the array are coupled to atleast one adjacent resonator;

FIG. 3A is a top view of one embodiment of a rounded triangle shapedMEMS resonator, having three elongated beam sections that are connectedvia rounded or curved sections, according to an embodiment of one aspectof the MEMS resonator array of the present inventions;

FIG. 3B is a top view of one embodiment of a rounded square shaped MEMSresonator, having four elongated beam sections that are connected viarounded or curved sections, according to an embodiment of one aspect ofthe MEMS resonator array of the present inventions;

FIG. 3C is a top view of one embodiment of a rounded hexagon shaped MEMSresonator, having six elongated beam sections that are connected viarounded or curved sections, according to an embodiment of one aspect ofthe MEMS resonator array of the present inventions;

FIGS. 4A-4I illustrate top views of exemplary MEMS resonator arrayshaving a plurality of rounded square shaped MEMS resonators according tocertain embodiments of the present inventions wherein the plurality ofrounded square shaped MEMS resonators are mechanically coupled to one ormore adjacent MEMS resonators of the MEMS resonator array employingvarious resonator coupling sections;

FIGS. 5A and 5B illustrate top views of exemplary MEMS resonator arrayshaving a plurality of rounded square shaped MEMS resonators according tocertain embodiments of the present inventions wherein the plurality ofrounded square shaped MEMS resonators are mechanically coupled to one ormore adjacent MEMS resonators of the MEMS resonator array employingvarious resonator coupling sections that include one or more loadingrelief mechanisms which are mechanically disposed within the resonatorcoupling section;

FIGS. 6A, 6B, 6D-6H, 7A-7H, 8A, 8B, 9A-9C, 10A and 10B illustrate topviews of exemplary MEMS resonator arrays having a plurality of roundedsquare shaped MEMS resonators according to certain embodiments ofpresent the inventions wherein one or more of the plurality of roundedsquare shaped MEMS resonators are mechanically coupled to one or moresubstrate anchors using various anchoring techniques and/orconfigurations;

FIG. 6C illustrates an oblique view of the MEMS resonator array of FIG.6D;

FIGS. 11A and 11B illustrate top views of a portion of exemplary MEMSresonator arrays including a rounded square shaped MEMS resonatoraccording to certain embodiments of the present inventions wherein theMEMS resonator array includes stress/strain relief mechanisms which aremechanically coupled between a rounded square shaped MEMS resonator anda substrate anchor;

FIGS. 12A-12C and 13A-13C illustrate top views of exemplary MEMSresonator arrays including a plurality of rounded square shaped MEMSresonators according to certain embodiments of the present inventionswherein each MEMS resonator array includes stress/strain reliefmechanisms which are mechanically coupled between one or more of therounded square shaped MEMS resonators and one or more substrateanchor(s);

FIGS. 14 and 15 are top views of a portion of exemplary embodiments ofrounded square shaped MEMS resonator, according to certain embodimentsof MEMS resonator array of the present inventions, wherein the roundedor curved sections have different radii, and a plurality of anchorcoupling sections that connect the rounded or curved sections to one ormore anchors;

FIGS. 16-18 are top views of various embodiments of anchor couplingsections in conjunction with a section of a MEMS resonator, according tocertain embodiments of the present inventions;

FIGS. 19-21 are top views of various embodiments of anchor couplingsections and stress/strain mechanisms, in conjunction with a section ofa MEMS resonator, according to certain embodiments of the presentinventions;

FIGS. 22A and 22B are top views of a ring oscillator that is oscillatingin plane in a breathing-like mode or motion, wherein the ring oscillatorexpands (FIG. 22A) and contracts (FIG. 22B) in relation to a non-inducedstate;

FIGS. 23A and 23B are top views of one embodiment of a rounded squareshaped MEMS resonator, including in-plane vibration of elongated beamsections, according to one aspect of present invention, wherein the MEMSresonator oscillates between a first deflected state (FIG. 23A) and asecond deflected state (FIG. 23B) and wherein each deflected state issuperimposed over (or illustrated relative to) the stationary state ofMEMS resonator;

FIGS. 24A and 24B are top views of an exemplary embodiment of a MEMSresonator array including four rounded square shaped MEMS resonators,having in-plane vibration of elongated beam sections, according to oneaspect of present invention, wherein the MEMS resonators oscillatebetween deflection states and wherein each deflected state issuperimposed over (or illustrated relative to) the stationary state ofMEMS resonator;

FIG. 25 illustrates an exemplary embodiment of a MEMS resonator arrayincluding four rounded square shaped MEMS resonators, in conjunctionwith drive and sense electrodes and drive and sense circuitry, accordingto an aspect of present invention;

FIGS. 26A and 26B illustrate exemplary embodiment of a MEMS resonatorarray including rounded square shaped MEMS resonators, in conjunctionwith a differential output signaling technique and embodiment, havingdrive and sense electrodes and differential drive and sense circuitry,according to exemplary embodiments of the present invention;

FIGS. 27A and 27B illustrate exemplary embodiments of a MEMS resonatorarray, including four rounded square shaped MEMS resonators, inconjunction with a differential output signaling technique andembodiment, having drive and sense electrodes and differential drive andsense circuitry, according to another embodiment of the presentinvention;

FIGS. 28A, 28B and 29A-29F illustrate exemplary embodiments of a MEMSresonator array, including four rounded square shaped MEMS resonators,in conjunction with various embodiments of drive and sense electrodes,according to exemplary embodiments of the present invention;

FIGS. 30A, 30B and 31-42 are top views of embodiments of a MEMSresonator array (or portions thereof) according to an aspect of theinvention, wherein the MEMS resonator device includes openings, voids orslots for improved manufacturability (for example, faster release of themechanical structures in those instances where the opening, void or slotextends the entire height/thickness of the beam section) and/or toimprove temperature management techniques (for example, decrease thermoelastic energy dissipation) implemented in one or more elongated beamsections, one or more curved sections, and/or one or more anchorcoupling sections;

FIGS. 43A and 43B illustrate top views of exemplary MEMS resonatorarrays having a plurality of rounded triangle shaped MEMS resonatorsaccording to certain exemplary embodiments of the present inventionswherein the plurality of triangle shaped MEMS resonators aremechanically coupled to one or more adjacent triangle shaped MEMSresonators of the MEMS resonator array;

FIGS. 43C and 43D illustrate top views of exemplary MEMS resonatorarrays having different shaped MEMS resonators including, a roundedtriangle shaped MEMS resonator mechanically coupled to a rounded squareshaped MEMS resonator (FIG. 43C) and rounded hexagon shaped MEMSresonators mechanically coupled to a rounded square shaped MEMSresonator (FIG. 43D);

FIGS. 44-46 are top views of various embodiments of exemplary MEMSresonator arrays including various exemplary anchor coupling sectionsand stress/strain mechanisms, in conjunction with a curved section of aMEMS resonator, according to certain embodiments of the presentinventions;

FIGS. 47 and 48 are top views of a portion of an exemplary MEMSresonator arrays including various exemplary anchoring techniques toanchor the MEMS resonator array (and/or the MEMS resonators thereof) tothe substrate;

FIGS. 49-52 are top views of exemplary MEMS resonator arrays includingvarious exemplary anchoring techniques and stress/strain mechanisms inconjunction with various exemplary embodiments of resonator mechanicalcoupling techniques, according to certain embodiments of the presentinventions;

FIGS. 53-55 are top views of exemplary MEMS resonator arrays includingvarious exemplary anchoring techniques and stress/strain mechanisms inconjunction with various exemplary embodiments of resonator mechanicalcoupling techniques and loading relief mechanisms, according to certainembodiments of the present inventions;

FIG. 56A is a top view of a MEMS frame array structure having aplurality of square shaped MEMS resonators, wherein each square shapedMEMS resonator of the array is coupled to the adjacent square shapedMEMS resonator and shares a beam section therewith, according to anotheraspect of the present inventions;

FIG. 56B illustrates an oblique view of the MEMS frame array structureof FIG. 56A;

FIGS. 57A, 58 and 59 illustrate top views of exemplary MEMS frame arraystructures having a plurality of square shaped MEMS resonators whereinone or more of the plurality of rounded square shaped MEMS resonatorsare mechanically coupled to an associated one of the substrate anchorsusing various anchoring techniques and/or configurations;

FIG. 57B illustrates an oblique view of the MEMS frame array structureof FIG. 57A;

FIG. 60A and 60B illustrate top views of a portion of exemplary MEMSframe array structures including a plurality of square shaped MEMSresonators according to one embodiment of present inventions wherein theMEMS frame array structure includes stress/strain relief mechanismswhich are mechanically coupled between (i) one or more of the squareshaped MEMS resonators and (ii) to a substrate anchor;

FIG. 61 is a top view of a MEMS frame array structure having a four byfour array of square shaped MEMS resonators, wherein each square shapedMEMS resonator of the array is coupled to the adjacent square shapedMEMS resonator, according to one aspect of present invention;

FIG. 62 is a top view of the MEMS frame array structure of FIG. 61wherein the square shaped MEMS resonators oscillate between deflectionstates (only one illustrated herein) and wherein each deflected state issuperimposed over (or illustrated relative to) the stationary state ofMEMS resonator;

FIGS. 63 and 64 illustrate top views of an exemplary MEMS frame arraystructure (in oscillation) having a plurality of square shaped MEMSresonators wherein two rounded square shaped MEMS resonators aremechanically coupled to an associated substrate anchor using variousanchoring techniques and/or configurations; and

FIG. 65 illustrates an exemplary embodiment of a MEMS frame arraystructure including four square shaped MEMS resonators, in conjunctionwith a differential output signaling technique and embodiment, havingdrive and sense electrodes and differential drive and sense circuitry,according to one embodiment of the present invention.

DETAILED DESCRIPTION

There are many inventions described and illustrated herein, as well asmany aspects and embodiments of those inventions. In one aspect, thepresent invention is directed to a plurality of mechanically coupledresonators that are arranged in an N×M MEMS array structure (where N andM are integers). Each of the resonators includes a plurality of straight(or substantially straight) elongated beam sections that are connectedby curved or rounded sections. Each elongated beam section of a givenresonator is connected to another elongated beam section at a distal endvia the curved or rounded sections thereby forming a geometric shapehaving at least two elongated beam sections that are interconnected viacurved or rounded sections.

Each resonator is mechanically coupled to at least one other resonatorof the MEMS array via a resonator coupling section. The resonatorcoupling sections are disposed or connected between elongated beamsections of mechanically coupled resonators. In this way, all of theresonators, when induced or during operation, vibrate at the same orsubstantially the same frequency. That is, in one embodiment, each beamsection of each resonator of the array oscillates or vibrates at thesame or substantially the same frequency oscillates or vibrates at thesame or substantially the same frequency.

In one embodiment, each MEMS resonator of a MEMS array of the presentinvention includes three elongated beam sections that are interconnectedvia curved sections to form a rounded triangle shape. In anotherembodiment, the MEMS array of the present invention includes a pluralityof resonators having four straight (or substantially straight) elongatedbeams that are connected, at distal ends, to rounded sections therebyforming a rounded square or rectangle shape.

In operation, when induced or during operation; each MEMS resonator ofthe array oscillates in a combined elongating (or breathing) mode andbending mode. In this regard, the beam sections of each MEMS resonatorof the array exhibit an elongating-like (or breathing-like) motion and abending-like motion. Further, when induced or during operation, eachbeam section of the MEMS resonators oscillates or vibrates at the sameor substantially the same frequency. The beam sections of the MEMSresonators of the array all exhibit the same or substantially the sameelongating-like (or breathing-like) motion and bending-like motion tothereby produce the same or substantially the same frequency.

The design and motion of each MEMS resonator of the array structure issuch that the resonator includes one or more nodal points or areas(i.e., portions of the resonator structure that are stationary,experience little movement, and/or are substantially stationary in oneor more degrees of freedom (whether from a rotational and/ortranslational perspective) during oscillation of the resonatorstructure). The nodal points are located in one or more portions orareas of the curved sections of the resonator structure. The nodalpoints are suitable and/or preferable locations to anchor the resonatorstructure and/or the array structure to the substrate. In this way,energy loss into the substrate may be minimized, limited and/or reduced,thereby enhancing the Q-factor of the resonator structure and/or thearray structure. Notably, such a configuration may minimize and/orreduce communication of stress and/or strain between the resonatingbeams of one or more resonators of the array and the substrate.

In addition, although the beam sections of each MEMS resonator of thearray, when induced or during operation, move in an elongating-like (orbreathing-like) manner (for example, like that of a ring oscillator) anda bending-like manner (for example, like that of a beam of adouble-claimed tuning fork), each MEMS resonator tends to maintain arelatively stable or fixed center of gravity. In this way, theresonators may avoid energy loss and thereby provide an array structurehaving a higher Q-factor.

Notably, the present inventions are described in the context ofmicroelectromechanical systems. The present inventions, however, are notlimited in this regard. Rather, the inventions described herein areapplicable to, for example, nanoelectromechanical systems. Thus, thepresent inventions are pertinent to microelectromechanical andnanoelectromechanical (herein collectively “MEMS” unless specificallynoted to the contrary) systems, for example, gyroscopes, resonators,and/or accelerometers, implementing one or more of the MEMS resonatorarray structures of the present inventions.

As mentioned above, in one aspect, the present invention is an array ofN×M MEMS resonators (where N and M are integers) coupled to one or moreof the adjacent MEMS resonators.

Each MEMS resonator is mechanically coupled to at least one otherresonator of the array via a resonator coupling section. With referenceto FIG. 2A, in one embodiment, MEMS resonator array 100 includes aplurality of MEMS resonators 102 a-d which are mechanically coupled, viaresonator coupling sections 104, to each adjacent MEMS resonator. Inthis way, each MEMS resonator 102 is coupled to all adjacent MEMSresonator(s) 102.

With reference to FIG. 2B, in another embodiment, MEMS resonator array100 includes a plurality of MEMS resonators 102 a-d which aremechanically coupled, via resonator coupling sections 104, to at leastone adjacent MEMS resonator. For example, MEMS resonator 102 e ismechanically coupled to adjacent MEMS resonators 102 b, 102 d, 102 f and102 h. In contrast, MEMS resonator 102 h is mechanically coupled toadjacent MEMS resonators 102 e and 102 k. In this embodiment, MEMSresonator 102 h is not coupled to adjacent MEMS resonators 102 g and 102i.

As mentioned above, each MEMS resonator of the MEMS resonator array,according to one aspect of the present invention, includes a pluralityof elongated beam sections that are connected by curved or roundedsections. Each elongated beam section is connected to another beamsection of the MEMS resonator at each distal end via the curved orrounded sections thereby forming a geometric shape having at least twoelongated beams that are interconnected via curved or rounded sections.In one embodiment, with reference to FIG. 3A, MEMS resonator 102includes three elongated beam sections 106 a-c that are connected viacurved sections 108 a-c to form a rounded triangle shape. With referenceto FIG. 3B, in another embodiment, MEMS resonator 102 includes fourelongated beam sections 106 a-d that are connected via curved sections108 a-d to form a rounded square shape.

Notably, MEMS resonator 102 of the present inventions may include morethan four elongated beam sections, for example, MEMS resonator 102 mayinclude six elongated beam sections 106 a-f that are connected togethervia curved sections 108 a-f to form a rounded hexagon shape (see, FIG.3C). Indeed, the resonator structure of the present inventions may takeany geometric shape whether now know or later developed that includestwo or more straight elongated beam sections which are interconnected bytwo or more curved or rounded sections.

The length and width of each beam section 106 and inner radii of thecurved sections 108 (and/or, more generally the shape of the radii ofthe curved sections) may determine one or more resonant frequencies ofMEMS resonator 102. The beam sections 106 oscillate or vibrate at thesame frequency. TABLE 1 provides a resonant frequency in conjunctionwith exemplary dimensions of the length and width of each beam section106 and inner radii of the curved sections 108 of rounded square MEMSresonator 102 which is fabricated from a polycrystalline siliconmaterial. Notably, in these exemplary embodiments, the width ofelongated beam sections 106 and curved sections 108 are the same orsubstantially the same.

TABLE 1 Resonant Elongated Beam Section Curved Section Frequency Width(μm) Length (μm) Inner Radius (μm) (MHz) Example 1 24 122.43 34.7875.3034

TABLE 2 provides a resonant frequency in conjunction with exemplarydimensions of the length and width of each beam section 106 and innerradii of the curved sections 108 of a rounded square MEMS resonator 102which is fabricated from a monocrystalline silicon material. Again, inthese exemplary embodiments, the width of elongated beam sections 106and curved sections 108 are the same or substantially the same.

TABLE 2 Resonant Elongated Beam Section Curved Section Frequency Width(μm) Length (μm) Inner Radius (μm) (MHz) Example 1 8 209.61 7.19441.1903 Example 2 24 129.89 31.055 4.8286

Notably, the dimensions of the MEMS resonators set forth in Tables 1 and2 are merely exemplary. The dimensions, characteristics and/orparameters of a MEMS resonator according to the present invention may bedetermined using a variety of techniques including modeling andsimulation techniques (for example, a finite element modeling and/orsimulation process implemented via a computer driven analysis engine,such as FEMLab (from Consol), ANSYS (ANSYS INC.), IDEAS and/or ABAKUS)and/or empirical data/measurements. For example, a finite elementanalysis engine, using or based on a set of boundary conditions (forexample, the size of the resonator structure), may be employed todesign, determine and assess the dimensions, characteristics and/orparameters of (i) elongated beam sections 106, (ii) curved sections 108,and (iii) other elements or properties of the resonator structure thatare discussed below. Notably, an empirical approach may also be employed(in addition to or in lieu of a finite element analysis (or the like)approach) to design, determine and assess the dimensions,characteristics and/or parameters of(i) elongated beam sections 106,(ii) curved sections 108, and (iii) other elements or properties of theresonator structure.

The MEMS resonators 102 of MEMS resonator array 100 are mechanicallycoupled via one or more resonator coupling sections 104. With referenceto FIGS. 4A-4C, in one embodiment, resonator coupling sections 104 maybe substantially straight beams having relatively uniform width.

Further, each of resonator coupling section 104 may have the same orsubstantially the same length and the same or substantially the sameshape. For example, with reference to FIGS. 4B and 4C, resonatorcoupling section 104 that mechanically couples MEMS resonators 102 a and102 b is substantially identical in shape and dimensions as resonatorcoupling sections 104 that mechanically couples MEMS resonators 102 band 102 c.

In another embodiment, resonator coupling sections 104 may besubstantially straight beams having different widths and/or lengths.(See, for example, FIGS. 4D and 4E).

In yet another embodiment, with reference to FIGS. 4F and 4G, resonatorcoupling sections 104 includes a design (for example, shape and width)of anchor coupling sections 116 to manage, control, reduce and/orminimize the stress concentration in or at the connection of resonatorcoupling sections 104 and elongated beams 106. In this embodiment,resonator coupling sections 104 are filleted to enhance the managementof the stresses between resonator coupling section 104 and associatedelongated beams 106. Such a design, however, may tend to increase theloading on elongated beams 106 relative to non-filleted designs. In thisregard, by adjusting the shape and width of resonator coupling section104 in the vicinity of elongated beam 106 (for example by filletingresonator coupling section 104 in the vicinity of elongated beam 106),the stress on resonator coupling section 104 and associated elongatedbeams 106 may be managed, controlled, reduced and/or minimized. In thisway, the durability and/or stability of MEMS resonator array 100 may beincreased, enhanced and/or optimized while the mode of operation or modeshape remains relatively undisturbed (or any disturbance is acceptable)and thereby the quality of the nodal points (discussed in more detailbelow), if any, remains relatively undisturbed (or any disturbance isacceptable). In addition thereto, reducing, minimizing and/or limitingthe loading on elongated beams 106 may facilitate an adverse impact onthe “Q” factor MEMS resonator array 100.

Other designs and/or configurations of resonator coupling section 104may be employed to, for example, affect the durability and/or stabilityof MEMS resonator array 100 as well as minimize, reduce or limit anyadverse impact on “Q” factor of MEMS resonator array 100. Indeed, alldesigns of resonator coupling section 104 whether now known or laterdeveloped are intended to fall within the scope of the presentinvention. For example, with reference to FIG. 4H and 4I, resonatorcoupling section 104 may include voids 110. The voids 110 may of anyshape or size and extend partially or entirely through theheight/thickness of coupling sections 104. Implementing voids in one ormore of the resonator coupling sections 104 reduces the mass ofresonator coupling section 104 which further minimizes, reduces orlimits the loading on elongated beam sections 106 and thereby furtherminimizes, reduces or limits any adverse impact on “Q” factor of MEMSresonator array 100. Notably, in certain embodiments, resonator couplingsections 104 have small dimensions (for example, the shape, length,width and/or thickness of resonator coupling sections 104) to provide asmall mass while adding little to no stiffness to elongated beamsections 106 is preferred.

With reference to FIGS. 5A and 5B, MEMS resonator array 100 of thepresent inventions may employ loading relief mechanisms 112 (forexample, springs or spring-like components) within an associatedresonator coupling section 104 to manage, control, reduce, eliminateand/or minimize any stress or strain on the associated pair of elongatedbeams 106 that are mechanically coupled by resonator coupling section104. In particular, loading relief mechanism 112 is disposed withinresonator coupling section 104 which mechanically couples elongated beam106 a of MEMS resonator 102 b and elongated beam 106 a of MEMS resonator102 c.

In operation, loading relief mechanisms 112 slightly expand and contractin conjunction with the motion of one, some or all of elongated beamsections 106 a-d and/or curved sections 108 a-d in order to reduce,eliminate and/or minimize any stress or strain on an associated theassociated elongated beam sections 106 a-d which are coupled byresonator coupling section 104. In addition, this coupling technique ofMEMS resonator array 100 may further reduce, eliminate and/or minimizeloading on the elongated beam sections 106 a-d thereby decreasing,reducing, minimizing and/or eliminating energy losses of MEMS resonators102 due to the mechanical coupling to adjacent MEMS resonators.

The loading relief mechanisms 112 may be employed in conjunction withany of the mechanical coupling techniques and/or architectures describedand/or illustrated herein. For example, loading relief mechanisms 112may be implemented within, before and/or after one or more of the one ormore resonator coupling section 104 of FIG. 5A and 5B.

Notably, loading relief mechanisms 112 may be well known springs orspring-like components, or may be any mechanism that reduces, eliminatesand/or minimizes stress and/or strain on coupled elongated beams 106.

As mentioned above, in operation, the motion of the MEMS resonator issuch that the MEMS resonator array and/or the individual MEMS resonatorsinclude one or more nodal points (i.e., areas or portions of theresonator structure that do not move, experience little movement, and/orare substantially stationary when the MEMS resonators oscillates). Itmay be advantageous to anchor the MEMS resonator array and/or theindividual MEMS resonators to the substrate through or at one or more ofthe nodal points of one or more of the individual MEMS resonators of theMEMS resonator array.

In one embodiment, the nodal points may be located in or near one ormore of curved sections of one or more of the MEMS resonators. Forexample, with reference to FIG. 6A, in one embodiment, MEMS resonators102 a and 102 b each include nodal points 114 located on or near anouter area, portion or region of curved sections 108. The anchorcoupling section 116 a is connected at or near nodal point 114 of MEMSresonator 102 a to secure, fix and/or connect MEMS resonator 102 a tothe substrate via anchor 118. Similarly, anchor coupling section 116 bis connected at or near nodal point 114 c of curved section 108 c ofMEMS resonator 102 b to secure, fix and/or connect MEMS resonator 102 bto the substrate via anchor 118. In this embodiment, MEMS resonator 102a and 102 b are separately connected to a common substrate anchor 118.

The MEMS resonator array 100 may be anchored to the substrate using avariety of anchoring techniques and/or configurations. In this regard,MEMS resonator 102 of MEMS resonator array 100 may be anchoredseparately to a common and/or individual anchor. For example, withreference to FIGS. 6C-6H, one or more of MEMS resonators 102 a-d areanchored to common anchor 118. In lieu of a common type anchoringstructure, one or more of MEMS resonators 102 a-d may be anchoredseparately to individual anchors. (See, for example, FIGS. 7A-7H). Inthis embodiment, MEMS resonator array 100 includes one or moreindividual anchors 118 that are “dedicated” to an associated MEMSresonator 102 of array 100.

Moreover, the anchoring structure of MEMS resonator array 100 mayinclude combinations or permutations of common and individual anchortechniques. (See, for example, FIGS. 8A and 8B). For example, withreference to FIG. 8A, MEMS resonators 102 a and 102 c are anchoredseparately to individual anchors 118 a and 118 b and MEMS resonators102B and 102 d are anchored to a common anchor 118 c. All combinationsand permutations of the various anchoring techniques are intended tofall within the scope of the present invention.

Notably, in those embodiments where MEMS resonator array 100 employ ananchor technique whereby anchor coupling sections 116 extend outwardfrom one or more curved sections 108, nodal points 114 may be located onor near an outer region or portion of curved sections 108. (See, forexample, FIGS. 6A-6H, 7A-7H, 8A and 8B). As such, one or more anchorcoupling sections 116 may connect MEMS resonators 102 to one or moresubstrate anchors 118, which are located “outside” each of the roundedsquare shape of MEMS resonators 102 a-d. In this anchoringconfiguration, outer regions or areas of curved sections 108 are nodalpoints 114 of MEMS resonators 102. Thus, by anchoring one or more ofMEMS resonators 102 a-d at or near the outer region or portion of curvedsection 108 (i.e., at or near one or more nodal points 114), thevertical and/or horizontal energy losses of MEMS resonator array 100and/or MEMS resonator 102 are minimized, limited and/or reduced.

In lieu of nodal points located on or near an outer area, portion orregion of one or more curved sections 108, one or more MEMS resonators102 may include nodal points 114 located on or near an inner area,portion or region of one or more curved sections 108. (See, for example,FIGS. 9A-9C). The anchor coupling sections 116 are connected at or nearnodal points 114, respectively, to secure, fix and/or connect one ormore of MEMS resonators 102 of MEMS resonator array 100 to the substratevia one or more anchors 118. In this way, MEMS resonator array 100 isanchored to the substrate via anchoring one or more of MEMS resonators102 to the substrate. In this embodiment, at least one MEMS resonator102 of the MEMS resonator array 100 is anchored according to thistechnique is coupled to an internal “center” anchor 118.

In addition to nodal points located on or near an outer area, portion orregion of one or more curved sections 108, MEMS resonators 102 mayinclude nodal points 114 located on or near an inner area, portion orregion of one or more curved sections 108. (See, for example, FIGS. 10Aand 10B). The anchor coupling sections 116 are connected at or nearnodal points 114 of one or more MEMS resonators 102 to secure, fixand/or connect MEMS resonator array 100 to the substrate. Thus, in thisembodiment, MEMS resonator array 100 employs both common anchoring andinternal “center” anchoring techniques.

Notably, MEMS resonator array 100 may be anchored to the substrate byanchoring one or more—but not all—of MEMS resonators 102 to thesubstrate. (See, for example, FIGS. 6G, 6H, 7C-H, 9C and 10B). Forexample, with reference to FIGS. 6G, MEMS resonators 102 b, 102 d, 102 fand 102 h are indirectly anchored to substrate anchor 118 via one, someor all of MEMS resonators 102 a, 102 c, 102 e and 102 g, which aredirectly connected to anchor 118 via anchor coupling sections 116. Thus,in these embodiments, one or more MEMS resonators 102 are directlyanchored to the substrate and one or more MEMS resonators 102 areindirectly anchored to the substrate. The one or more MEMS resonatorsthat are directly anchored to the substrate may be anchored to a“common” type anchor (see, for example, FIGS. 6G and 6H) or an“individual” type anchor (see, for example, FIGS. 7C-7H, 9C), or both(see, FIGS. 8A, 8B and 10B).

With reference to FIGS. 11A, 11B, 12A-12C and 13A-13C, MEMS resonatorarray 100 of the present inventions may employ stress/strain reliefmechanisms 120 (for example, springs or spring-like components) tomanage, control, reduce, eliminate and/or minimize any stress or strainon the substrate at the location of the anchor 118 which is caused bythe motion of one, some or all of points at which MEMS resonator array100 is anchored through or at the substrate. For example, with referenceto FIGS. 11A and 11B, curved portions 108 of MEMS resonator 102 a ismechanically coupled to stress/strain relief mechanism 120 via anchorcoupling section 116.

With reference to FIGS. 12A-12C and 13A-13C, in operation, stress/strainrelief mechanisms 120 expand and contract in conjunction with the motionof one, some or all of elongated beam sections 106 a-d and curvedsections 108 a-d of MEMS resonators 102 a-d in order to reduce,eliminate and/or minimize any stress or strain on the substrate and/orto compensate for small remaining movements of the anchoring point dueto small asymmetries from manufacturing, material properties may changethereby resulting in a non-100% optimized design (even where FiniteElement Modeling (also known as Finite Element Analysis, “FEA” or “F EAnalysis”) is employed). In this way, the anchoring architecture of MEMSresonator array 100 may be relatively stress-free and/or strain-freewhich may significantly decrease, reduce, minimize and/or eliminate anyanchor energy loss and thereby increase, enhance, maximize the Q (andoutput signal) of MEMS resonators 102 and anchor stress will have littleto no effect on the resonating frequency of MEMS resonators 102.Notably, stress/strain relief mechanism 120 and anchor coupling section116, in addition to decreasing, reducing, minimizing and/or eliminatinganchor energy losses, suspend MEMS resonators 102 (including elongatedbeam sections 106 and curved sections 108) of MEMS resonator array 100above the substrate.

The stress/strain relief mechanisms 120 may be employed within one ormore of the one or more anchor coupling section 116. It may beadvantageous to implement stress/strain relief mechanisms 120 in thosesituations where the point at which MEMS resonator array 100 is anchoredthrough or at the substrate is not sufficiently or adequately motionless(i.e., where there is undesirable movement of the curved section 108 orcoupling section 116 which may originate from or be caused by one ormore MEMS resonators 102 or the substrate) or where additionalde-coupling from the substrate is desired. For example, it may also beadvantageous to employ stress/strain relief mechanisms 120 to reduce,eliminate and/or minimize communication of energy between one or moreMEMS resonators 102 and the substrate (for example, in those situationswhere there is an impedance mismatch to a curved section 108 or where“noise” originates in the substrate and is communicated to one or moreMEMS resonator 102).

The stress/strain relief mechanisms 120 may be employed in conjunctionwith any of the anchoring techniques and/or architectures describedand/or illustrated herein. For example, stress/strain relief mechanisms120 may be implemented within one or more of the one or more anchorcoupling section 116 of FIG. 12A-12C and/or FIG. 13A-13C.

The stress/strain relief mechanisms 120 may be well known springs orspring-like components, or may be any mechanism that reduces, eliminatesand/or minimizes: (i) stress and/or strain on the substrate at thelocation of the anchor which is caused by the motion of one, some or allof points at which one or more MEMS resonators 102 are anchored throughor at the substrate, and/or (ii) communication of energy between one ormore MEMS resonators 102 and the substrate.

Notably, MEMS resonators 102 need not be anchored at every nodal pointor area but may be anchored at one or more locations, preferably at oneor more nodal locations (areas or locations of the resonator that do notmove, experience little movement, and/or are substantially stationarywhen the resonator oscillates). For example, with reference to FIGS.7A-7F, MEMS resonator array 100, may be anchored at one point, twopoints and/or three areas or portions of MEMS resonators 102(preferably, for example, at or near nodal points 106 of one or moreMEMS resonators 102). In this regard, one or more anchor couplingsections 116 connect(s) elongated beam sections 106 and curved section108 of MEMS resonator(s) 102 to corresponding anchors 118.

A finite element analysis and simulation engine may also be employed todesign, determine and/or define the location(s) of one or more nodalpoints at which MEMS resonator 102 may be anchored to the substrate withpredetermined, minimal and/or reduced energy loss (among other things).In this regard, beam sections 108 of MEMS resonator 102, when inducedduring operation, move in an elongating (or breathing-like) manner and abending manner. As such, the length of elongated beam sections 106 andthe radii of curved sections 108 may determine the location of nodalpoints on or in the resonator structure whereby there is little, no orreduced rotation movement due to the elongating (breathing-like) mode,as well as little, no or reduced radial movement due to the bending-likemode. The finite analysis engine may be employed to design, determineand assess the location of such nodal points in or on MEMS resonator 102using a given length of elongated beam sections 106, and the shapeand/or the radii of curved sections 108 of MEMS resonator 102. In thisway, areas or portions in or on curved sections 108 of MEMS resonator102 that exhibit acceptable, predetermined, and/or little or no movement(radial, lateral and/or otherwise) for anchoring MEMS resonator 102 maybe rapidly determined and/or identified.

Notably, a finite element analysis and simulation engine may also beemployed to design, determine, assess and/or define the location(s) ofone or more nodal points of MEMS resonators 102 when implemented in MEMSresonator array 100. In addition, an empirical approach may also beemployed (in addition to or in lieu of a finite element analysis andsimulation engine (or the like)) to design, determine, assess and/ordefine the location(s) of one or more nodal points of MEMS resonators102 when implemented in MEMS resonator array 100. Indeed, the entirediscussion above regarding finite element analysis and simulation engineis pertinent to the design, analysis and response of MEMS resonatorarray 100 having a plurality of MEMS resonators 102. For the sake ofbrevity those discussions will not be repeated.

The MEMS resonator array of the present invention employ any anchorstructure and technique whether now known or later developed. Indeed,all structures and techniques are intended to fall within the scope ofthe present invention. For example, the present invention may employ theanchoring structures and techniques described and illustrated innon-provisional patent application entitled “Anchors forMicroelectromechanical Systems Having an SOI Substrate, and Method forFabricating Same”, which was filed on Jul. 25, 2003 and assigned Ser.No. 10/627,237 (hereinafter “Anchors for Microelectromechanical SystemsPatent Application”). It is expressly noted that the entire contents ofthe Anchors for Microelectromechanical Systems Patent Application,including, for example, the features, attributes, alternatives,materials, techniques and advantages of all of the embodiments and/orinventions, are incorporated by reference herein.

In those embodiments where one or more of MEMS resonators 102 areanchored to a “center” anchor 118 (see, for example, 9A-9C, 10A and10B), the design (for example, the shape and width) of anchor couplingsections 116 may impact the inner radii of curved sections 108 andthereby (i) the location of nodal points (if any) in or on MEMSresonator 102 as well as (ii) the resonant frequency of MEMS resonator102. In addition to impacting the inner radii of curved sections 108,the design of anchor coupling section 1 16 may also affect thedurability and/or stability of MEMS resonator 102. In this regard, byadjusting the shape and width of the anchor coupling section 116 in thevicinity of curved section 108 (for example by filleting anchor couplingsection 116 in the vicinity of curved section 108 as shown in FIGS. 14and 15), the stress on MEMS resonator 102 may be managed, controlled,reduced and/or minimized.

For example, with reference to FIGS. 14 and 15, the width of anchorcoupling section 116 may be increased (see, for example, FIG. 15relative to FIG. 14) to manage, control, reduce and/or minimize thestress concentration in or at nodal points 114. In this way, thedurability and/or stability of MEMS resonator 102 may be increased,enhanced and/or optimized.

Other designs and/or configurations of anchor coupling sections 116 maybe employed to, for example, affect the durability and/or stability ofMEMS resonator 101 as well as impact the inner radii of curved sections108 and the location of nodal points (if any) and the resonant frequencyof MEMS resonator 102. (See, for example, FIGS. 16-21). Indeed, alldesigns of anchor coupling sections 116 whether now known or laterdeveloped are intended to fall within the scope of the presentinvention.

Notably, the shape and/or width of elongated beam section 106 in thevicinity of curved section 108 may also impact the durability and/orstability of MEMS resonator 102 (and in particular, the stress in curvedsections 108 which are employed as anchoring locations) as well asimpact the inner radii of curved sections 108 and the location of nodalpoints (if any) and the resonant frequency of MEMS resonator 102. Inthis regard, by widening elongated beam section 106 in the vicinity ofcurved section 108 and/or filleting elongated beam section 106 in thevicinity of curved section 108, the stress on the resonator may bereduced and/or minimized.

Thus, in one embodiment, by controlling the shape and width of elongatedbeam sections 106 and/or anchor coupling section 116, the inner radii ofcurved sections is defined thereby defining the relationship between thewhether and how curved sections 108 move relative to elongated beamsections 106. In addition to determining the inner radii of curvedsections 108 and, as such, the locations of nodal points 114, the shapeof elongating beam sections 106 and/or anchor coupling section 116 inthe vicinity of curved section 108 may affect the durability andstability of MEMS resonator 102. In this regard, by widening elongatedbeam section 106 in the vicinity of curved section 108 and/or widening(or filleting) the anchor coupling section 116, the stress on MEMSresonator 102 may be managed, controlled, reduced, minimized and/oroptimized.

Notably, as mentioned above, the curvature and/or shape of curvedsections 108 may be selected and/or designed to include one or morenodal points or areas in or in the vicinity of curved sections 108. Forexample, where curved section 108 moves out-of-phase with elongated beamsection 106 connected thereto, the radius of a particular curved section108 may be too small. Conversely, if the radius of a particular curvedsection 108 is too large, curved section 108 may move in-phase with beamsections 106 that are connected to curved section 108. In each instance,the particular curved section 108 may or may not include a nodal pointthat minimizes or reduces energy loss and/or substrate stress.

The aforementioned relationship is discussed in detail in“Microelectromechanical Resonator Structure, and Method of Designing,Operating and Using Same”, filed May 19, 2005, and assigned U.S. patentapplication Ser. No. 11/132,941. The inventions described andillustrated in the aforementioned patent application may be employed todesign; implement, and/or fabricate one or more of the MEMS resonatorsof the MEMS resonator array of the present invention. For the sake ofbrevity, those discussions will not be repeated. It is expressly noted,however, that the entire contents of the patent application, including,for example, the features, attributes, alternatives, materials,techniques and/or advantages of all of the inventions/embodiments, areincorporated by reference herein.

In operation, beam sections 106 of each MEMS resonator 102 of array 100oscillate or vibrate at the same frequency. In this regard, beamsections 106 oscillate in an elongating (or breathing) motion or mode(for example, like that of a ring oscillator; see ring oscillator 1000of FIG. 22A (expanding motion—ring oscillator 1000′) and FIG. 22B(contracting motion—ring oscillator 1000″)) as well as a bending motionor mode. Focusing on one MEMS resonator 102 of MEMS resonator array 100,in one embodiment, during operation, beam sections 106 a-d of roundedsquare shaped MEMS resonator 102 oscillate between a first deflectedstate (see, FIG. 23A) and a second deflected state (see, FIG. 23B). Eachdeflected state in FIGS. 23A and 23B is superimposed over (orillustrated relative to) the stationary state of beam sections 106 andcurved sections 108 of MEMS resonator 102.

Notably, when in the first deflected state, in addition to bending, beamsections 106 a-d elongate by an amount of ΔL1. Similarly, in the seconddeflected state, beam sections 106 a-d elongate by an amount of ΔL2 andbend in the opposite direction to that of the first deflected state. Theamount of elongation (i.e., ΔL1 and ΔL2) may or may not be equal.

Moreover, with continued reference to FIGS. 23A and 23B, nodal points114 a -d in or on curved sections 108 a-d experience little to nomovement during operation. That is, as MEMS resonator 102 oscillatesbetween the first deflected state and the second deflected state, theareas or portions of curved sections 108 a-d which are connect to anchorcoupling sections 116 are relatively stationary. The anchors are notillustrated.

Notably, each MEMS resonator 102 of MEMS resonator array 100 mayoscillate in an inherently or substantially linear mode. As such, theconsiderations and requirements of the drive and sense circuitry,discussed below, to provide a linear resonator/oscillator may be lessstringent and/or complex because there may be no need to very preciselyor very accurately control the resonant amplitude of beam sections 106.In this regard, some resonator structures (for example, resonatorshaving double-clamped beams, such as double-clamped tuning forks) havemodes that are non-linear wherein the output frequency is a function ofthe resonant amplitude. This effect is evident when a beam transitionsfrom a bending mode transitions to a tensile (elongating) mode. Adouble-clamped beam, in a primary mode, may exhibit this behaviorbecause at smaller amplitudes the “restring” forces are dominated bybending stress and, at larger amplitudes, the resorting force isdominated by tensile stress. Under this situation, to maintain aconstant frequency in such a case the resonant amplitude of the beam mayneed to be carefully regulated, which may be difficult and likelyintroduces additional complexity.

Focusing now on MEMS resonator array 100, with reference to FIGS. 24Aand 24B, in one embodiment, during operation, beam sections 106 a-d ofeach rounded square shaped MEMS resonator 102 oscillate between thefirst deflected state and the second deflected state—but in an oppositedirection relative to beam sections 106 a-d of an adjacent MEMSresonator 102. In this regard, opposing beam sections 106 of adjacentMEMS resonators 102 oscillate, in relation to the other, in-phase—but inopposite directions—between the first deflected state and the seconddeflected state. That is, when beam section 106 b of MEMS resonator 102a is in a first deflected state, beam section 106 d of MEMS resonator102 b (i.e., the beam section opposing beam section 106 b of MEMSresonator 102 a) is in a second deflected state. (See, FIG. 24A).Similarly, when beam section 106 b of MEMS resonator 102 a is in asecond deflected state, beam section 106 d of MEMS resonator 102 b is ina first deflected state. (See, FIG. 24B). In this way, beams sections106 a-d of MEMS resonators 102 a-d of array 100 oscillate or vibrate atthe same or substantially the same frequency. Moreover, resonatorcoupling sections 104 experience relative little to no expansion orcontraction as the beams oscillate between the first and seconddeflected states.

Notably, the deflected states in FIG. 24A and 24B is superimposed over(or illustrated relative to) the stationary state of beam sections 106and curved sections 108 of MEMS resonators 102 a-d.

The sense and drive electrodes and circuitry may be configured toprovide a single-ended output signal or differential output signals.With reference to FIG. 25, in one exemplary embodiment of a single-endedoutput signal configuration, drive electrodes 122 (which areelectrically connected to drive circuitry 124) are juxtaposed to beamsections 106 a-d of MEMS resonators 102 b and 102 d to induce beamsections 106 a-d of resonators 102 b and 102 d to oscillate or vibratewherein the oscillation or vibration has one or more resonantfrequencies. The sense circuitry 126, in conjunction with senseelectrodes 128 which are also juxtaposed to beam sections 106 a-d ofMEMS resonators 102 a and 102 c, sense, sample and/or detect a signalhaving the one or more resonant frequencies. In this regard, senseelectrodes 128 are disposed adjacent to beam sections 106 to provide asignal (for example, resulting from a change in capacitance between beamsections 106 and sense electrodes 128 due to the oscillating motion ofeach MEMS resonator structure) which is representative of theoscillation or vibration to sense circuitry 126. The sense circuitry 126receives the signal and, in response thereto, may output a signal, forexample, a clock signal having a resonant frequency. Typically the sensesignal output is connected to the drive circuit 124 to close theelectronic oscillator loop. In this regard, the phase of the drivesignal should be appropriate to stimulate/drive the desired mode.

Notably, drive circuitry 124 and sense circuitry 126, as well as driveelectrodes 122 and sense electrodes 128, may be conventional well-knowndrive and sense circuitry. Indeed, drive circuitry 124 and sensecircuitry 126 may be any MEMS sense and drive circuitry whether nowknown or later developed.

In addition, drive electrodes 122 and sense electrodes 128 may bedisposed or positioned relative to beam sections 106 in order to detectone or more selected or predetermined harmonics of beam sections 106 ofMEMS resonators 102. Moreover, the number and length of drive electrodes122 and sense electrodes 128 may be selected in order to optimize,enhance and/or improve the operation of MEMS resonator array 100 and/orMEMS resonators 102. Indeed, drive electrodes 122 and sense electrodes128 may be of any type and/or shape whether now known or laterdeveloped.

Moreover, drive circuitry 124 and/or sense circuitry 126 may beintegrated on the same substrate in which MEMS resonator array 100resides (or is fabricated in). In addition thereto, or in lieu thereof,drive circuitry 124 and/or sense circuitry 126 may be integrated on asubstrate that is physically separate from (and electricallyinterconnected with) the substrate in which MEMS resonator array 100resides.

In another embodiment, MEMS resonator array 100 is configured to providea differential output signal. In this embodiment, the sense and driveelectrodes and circuitry are configured to provide output signals thatare (or are substantially) 180 degrees out of phase. In this way, MEMSresonator array 100 provides a differential output signal pair whichincludes a relatively large signal to noise relationship due to thesumming effects of oscillating beam sections 106 (for example,symmetrical oscillating beam sections) of the plurality of MEMSresonators 102.

With reference to FIG. 26A, in one exemplary embodiment of adifferential output signal configuration, drive electrodes 130 and 132(which are electrically connected to differential drive circuitry 138)are juxtaposed to beam sections 106 a-d of MEMS resonator 102 a and 102b to induce beam sections 106 a-d of MEMS resonator 102 a and 102 b tooscillate or vibrate. In this regard, each MEMS resonator 102 vibratesor resonates, in-plane, to generate output signals that are (or aresubstantially) 180 degrees out of phase. The sense electrodes 134 and136 are disposed adjacent to beam sections 106 a-d of MEMS resonator 102c and 102 d to provide a signal (for example, resulting from a change incapacitance between beam sections 106 and sense electrodes 134 and 136due to the oscillating motion of the resonator structure) which isrepresentative of the oscillation or vibration to differential sensecircuitry 140 which senses, samples and/or detects a signal having theone or more resonant frequencies. The differential sense circuitry 140receives the signal and, in response thereto, may output a differentialsignal pair, for example, a differential clock signal having a resonantfrequency.

The differential drive circuitry 138 and differential sense circuitry140 may be conventional well-known circuitry. Indeed, differential drivecircuitry 138 and differential sense circuitry 140 may be any type ofcircuitry (whether or not integrated (or fabricated) on the samesubstrate in which the MEMS resonator structure resides), and all suchcircuitry, whether now known or later developed, are intended to fallwithin the scope of the present invention.

In addition, drive electrodes 130 and 132, and sense electrodes 134 and136, may be of a conventional, well known type or may be any type and/orshaped electrode whether now known or later developed. Further, thephysical electrode mechanisms may include, for example, capacitive,piezoresistive, piezoelectric, inductive, magnetorestrictive andthermal. Indeed, all physical electrode mechanisms whether now known orlater developed are intended to fall within the scope of the presentinvention.

In addition, drive electrodes 130/132 and sense electrodes 134/136 maybe disposed or positioned relative to beam sections 106 of MEMSresonators 102 in order to detect one or more selected or predeterminedharmonics of beam sections 106. Moreover, the number and length of driveelectrodes 130/132 and sense electrodes 134/136 may be selected in orderto optimize, enhance and/or improve the operation of the MEMS resonator.

Notably, differential drive circuitry 138 and differential sensecircuitry 140 maybe integrated on the same substrate in which the MEMSresonator structure resides (or is fabricated in). In addition thereto,or in lieu thereof, differential drive circuitry 138 and differentialsense circuitry 140 may be integrated on a substrate that is physicallyseparate from (and electrically interconnected with) the substrate inwhich the MEMS resonator structure resides.

In the embodiment of FIG. 26A, drive electrodes 130/132 and senseelectrodes 134/136, are symmetrically configured, which in conjunctionwith the symmetrical structures of MEMS resonators 102, manage thestress on resonator coupling sections 104, beam sections 106, curvedsections 108, anchor coupling sections 116, anchors 118 and/or thesubstrate. In this way, resonator coupling sections 104 and/or anchorcoupling sections 116 may be a low stress point which may manage,minimize and/or reduce energy loss of one, some or all of MEMS resonator102 of MEMS resonator array 100.

Notably, the differential and single-ended output signal configurationsmaybe implemented in MEMS resonator arrays 100 having less than orgreater than four MEMS resonators 102. (See, for example, thedifferential output signal configuration of FIG. 26B). Indeed, all ofthe features, embodiments and alternatives discussed herein with respectto MEMS resonator array 100 in the context of sensing and driving thearray are applicable to arrays of any size (for example, an array having2, 3, 4, 5, 6, 7 and 8 MEMS resonators 102) and/or configuration (forexample, arrays comprised of the same or different geometric shapes ofMEMS resonators 102 such as rounded squares, rounded hexagons or roundedtriangles). For the sake of brevity, those discussions will not berepeated.

Further, it should be noted that there are many other configurationsand/or architectures of the sense and drive electrodes that cause orinduce beam sections 106 to resonate and thereby generate and/or produceoutput signals that are (or are substantially) 180 degrees out of phase.The MEMS resonator array 100 of the present invention may employ anysense and drive structure, technique, configurations and/orarchitectures whether now known or later developed. For example, thedrive and sense electrodes may be of a conventional type or may be anytype and/or shape. (See, for example, FIGS. 27A and 27B). The number anddesign of drive and/or sense electrodes may be selected to provideaddition drive signal and/or sense signal. For example, in oneembodiment, the number of sense electrodes, and the cross-sectionalsense electrode-beam section interface, is increased in order toincrease the signal provided to sense circuitry (for example, thedifferential sense circuitry). (See, for example, FIG. 28A). In oneembodiment, sense electrodes are disposed on the inner and outerperimeters of one or more of MEMS resonators 102. (See, for example,FIG. 28B). Thus, MEMS resonator array 100 of the present invention mayemploy any sense and drive electrode structure and configuration whethernow known or later developed. (See, for example, FIGS. 29A-29F).

Moreover, implementing a differential signal configuration mayfacilitate canceling, limiting, reducing and/or minimizing the effect ofcapacitive coupling from the drive electrodes to the sense electrodes.In addition, a fully differential signaling configuration may alsosignificantly decrease any sensitivity to electrical and/or mechanicalnoise coupled from the substrate. Further, implementing MEMS resonatorarray 100 in a differential signaling configuration may also eliminate,minimize and/or reduce charge flow through the anchor to and from thestructure. As such, a voltage drop between the substrate anchor anddrive and sense electrodes may be avoided. Notably, this voltage dropcould degrade or adversely impact the electric transfer function of theMEMS resonators of the array especially at higher frequencies (forexample, frequencies greater than 100 MHz).

In one embodiment of the present invention, MEMS resonator array 100employs temperature management techniques in order to manage and/orcontrol the Q factor of MEMS resonators 102. In this regard, when beamsections 106 and/or curved sections 108 bend, one side of the section isstretched thereby causing a slight cooling in the area of thestretching, and the other side is compressed, thereby causing a slightheating in the area of the compression. The heat gradient causesdiffusion from the “hotter” side to the “cooler” side. The diffusion ofheat (“heat flow”) results in a loss of energy, which may impact (forexample, reduce) the Q factor of MEMS resonator 102. This effect isoften referred to as Thermoelastic Dissipation (“TED”), which may be adominate limit of the Q factor of a resonant structure. As such, is maybe advantageous to implement temperature management techniques in orderto manage, control, limit, minimize and/or reduce TED.

In one temperature management embodiment, with reference to FIGS. 30Aand 30B, slots 142 are formed in one or more of beam sections 106 a-dand curved sections 108 a-d of MEMS resonator 102. The slots 142suppress/reduce heat flow between the sides of beam sections 106 a-d andthe sides of curved sections 108 a-d as beam sections 106 a-d and curvedsections 108 a-d stretch and compress during operation. Thesuppression/reduction of heat transfer within the beam sections 106 a-dand curved sections 108 a-d may lead to a higher Q factor for MEMSresonator 102 and MEMS resonator array 100. It has to be noted that themethods of temperature management by using slots affects theoptimization of the zero movement at the anchoring point and has to beconsidered by the design (for example, FEA).

The temperature management techniques may be employed in one or morebeam sections 106 or one or more curved sections 108 of one or more MEMSresonators 102 (see, for example, FIGS. 31, 34, 38 and 41), or both(see, for example, FIGS. 32, 33, 35, 37 and 42). In addition thereto, orin lieu thereof, the temperature management techniques may also beimplemented in anchor coupling sections 116. (See, for example, FIGS.36, 41 and 42). The slots 142 may be any shape including, for example,square, rectangle, circular, elliptical and/or oval. Indeed, slots 142of any shape, whether geometric or otherwise, may be incorporated intobeam sections 106, curved sections 108 and/or anchoring couplingsections 116.

Notably, slots 142 may also change the stiffness of the beam sections106, curved sections 108 and/or anchoring coupling sections 116.

There are many inventions described and illustrated herein. Whilecertain embodiments, features, materials, configurations, attributes andadvantages of the inventions have been described and illustrated, itshould be understood that many other, as well as different and/orsimilar embodiments, features, materials, configurations, attributes,structures and advantages of the present inventions that are apparentfrom the description, illustration and claims. As such, the embodiments,features, materials, configurations, attributes, structures andadvantages of the inventions described and illustrated herein are notexhaustive and it should be understood that such other, similar, as wellas different, embodiments, features, materials, configurations,attributes, structures and advantages of the present inventions arewithin the scope of the present invention.

Notably, although a significant portion of the description of thepresent inventions was set forth in the context of a MEMS resonatorarray including a plurality of rounded square shaped MEMS resonators, aMEMS resonator array according to the present invention may include MEMSresonators of any geometric shaped resonator architecture or structureincluding a plurality of elongated beam sections that are connected bycurved or rounded sections. For example, as mentioned above, in oneembodiment, the MEMS resonator array of the present inventions mayinclude three elongated beam sections that are connected together viacurved sections to form a rounded triangle shape, as illustrated in FIG.3A. In another embodiment, the MEMS resonator array of the presentinvention may include six beam sections and six curved sections asillustrated in FIG. 3C. All of the features, embodiments andalternatives discussed herein with respect to a MEMS resonator having arounded square shape are applicable to MEMS resonators, according to thepresent invention, which have other shapes. (See, for example, FIGS. 43Aand 43B). Moreover, all of the features, embodiments and alternativesdiscussed herein with respect to MEMS resonator array 100 having aplurality of rounded square shaped resonators are applicable to MEMSresonators, according to the present invention, which have other shapes.For the sake of brevity, those discussions will not be repeated.

In another embodiment, the MEMS resonator array of the present inventionmay include a plurality of MEMS resonators 102 having different shapes.For example, with reference to FIG. 43C, rounded square shaped MEMSresonator 102 a may be mechanically coupled to rounded triangle shapedMEMS resonator 102 b (FIG. 43C). With reference to FIG. 43D, in anotherexample, rounded hexagon shaped MEMS resonators 102 a and 102 c maybemechanically coupled to rounded square shaped MEMS resonator 102 b. Allof the features, embodiments and alternatives discussed herein withrespect to a MEMS resonator array 100 having a plurality of roundedsquare shaped resonators are applicable to MEMS resonator arrayincluding a plurality of MEMS resonators 102 having two or moredifferent shapes. For the sake of brevity, those discussions will not berepeated.

Further the MEMS resonator array of the present invention may employ anysense and drive techniques whether now known or later developed. Thedrive and sense circuitry (whether differential or not) may beintegrated on the same substrate in which the MEMS resonators of thearray resides (or is fabricated in). In addition thereto, or in lieuthereof, drive and sense circuitry may be integrated on a substrate thatis physically separate from (and electrically interconnected with) thesubstrate in which the MEMS resonators resides. Moreover, the drive andsense electrode may be of a conventional type or may be any type and/orshape whether now known or later developed.

Notably, the dimensions, characteristics and/or parameters of the MEMSresonators and MEMS resonator array according to the present inventionsmay be determined using a variety of techniques including finite elementmodeling and simulation techniques (for example, a finite elementmodeling via a computer driven analysis engine such as FemLab (fromConsol), ANSYS (from ANSYS INC.), IDEAS and/or ABAKUS and/or empiricaldata/measurements. For example, a finite element modeling engine, usingor based on a set of boundary conditions (for example, the size of theresonator structure), may be employed to design, determine and/or assessthe dimensions, characteristics and/or parameters of (i) elongated beamsections 106, (ii) curved sections 108, (iii) loading relief mechanisms112, (iv) nodal point(s) 114 (if any), (v) anchor coupling sections 116and/or (vi) stress/strain mechanisms 120. Indeed, the impact and/orresponse of MEMS resonator 102, alone or incorporated into a MEMSresonator array 100, on or at the anchor and/or substrates may also beobserved and/or determined using such a finite element modeling,simulation and analysis engine.

As mentioned above, a finite element analysis and simulation engine mayalso be employed to design and/or determine the location of any nodalpoints. Such nodal points may provide a suitable location at which MEMSresonator array 100 (and/or one or more of MEMS resonator 102) may beanchored to the substrate with predetermined, minimal and/or reducedenergy loss (among other things). In this regard, beam sections 106 ofMEMS resonator 102, when induced, move in a breathing-like manner and abending-like manner. As such, the length of beam sections 106 and theradii of curved sections 108 may determine the location of nodal pointsof MEMS resonator 102 (when incorporated into the MEMS resonator array100) whereby there is little, no or reduced rotation movement due to theelongating-like (breathing-like) mode, as well as little, no or reducedradial movement due to the bending-like mode. A finite element analysisengine may be employed to design, determine or predict the location ofsuch nodal points based on a given length of beam sections 106 and theradii of curved sections 108 of each MEMS resonator 102 of MEMSresonator array 100. In this way, locations that exhibit acceptable,predetermined, and/or little or no movement (radial and/or otherwise)for anchoring MEMS resonator array 100 and/or one or more MEMSresonators 102 may be rapidly determined and/or identified.

Moreover, an empirical approach may also be employed (in addition to orin lieu of a finite element analysis (or the like) approach) to design,determine, define and/or assess the dimensions, characteristics and/orparameters of (i) elongated beam sections 106, (ii) curved sections 108,(iii) loading relief mechanisms 112, (iv) nodal point(s) 114 (if any),(v) anchor coupling sections 116 and/or (vi) stress/strain mechanisms120. Such an empirical approach may be implemented in the context of oneor more MEMS resonators 102 and/or MEMS resonator array 100.

As mentioned above, in the context of MEMS resonator array 100, a finiteelement analysis 1 5 and simulation engine, using or based on a set ofboundary conditions (for example, the size of the resonator structure),may be employed to design, determine and/or assess the dimensions,characteristics and/or parameters of(i) elongated beam sections 106,(ii) curved sections 108 and/or (iii) nodal point(s) 114 (if any) of theMEMS resonators 102, and/or (iv) loading relief mechanisms 112, (v)anchor coupling sections 116 and/or (vi) stress/strain mechanisms 120.

Further, a thermo-mechanical finite element analysis engine may beemployed to enhance any temperature considerations of beam sections 106,curved sections 108 and/or anchoring coupling sections 116 duringoperation. In this regard, thermo-mechanical finite element analysisengine may model the operation of MEMS resonator array 100 and/or MEMSresonators 102 and thereby determine the size, location, dimensions, andnumber of slots to implement in one or more beam sections 106, curvedsections 108 and/or anchoring coupling sections 116. In this way, thecharacteristics of MEMS resonator array 100 and/or MEMS resonators 102,having temperature management techniques implemented therein, may beenhanced and/or optimized and the TED loss minimized and/or reduced.

Thus, as mentioned above, many of the properties of the structures ofthe present inventions may be optimized with Finite Element Modeling(FEM), which is also known as “FEA” or “FE Analysis”.

The beam sections 106 of MEMS resonators 102 may or may not includeidentical or substantially identical dimensions/designs (i.e., have thesame or substantially the same width, thickness, height, length and/orshape). In addition, curved sections 108 may or may not includeidentical or substantially identical dimensions/designs (i.e., have thesame or substantially the same inner radius, width, thickness, height,length, outer radius and/or shape). As such, MEMS resonators 102 ofarray 100 may include beam sections 106 and/or curved sections 108having different dimensions, shapes and/or designs.

The MEMS resonator array of the present inventions may be fabricatedfrom well-known materials using well-known techniques. For example, theMEMS resonator array (including its constituent parts) may be fabricatedfrom well-known semiconductors such as silicon, germanium,silicon-germanium or gallium-arsenide. Indeed, the MEMS resonator arraymay be comprised of, for example, materials in column IV of the periodictable, for example silicon, germanium, carbon; also combinations ofthese, for example, silicon germanium, or silicon carbide; also of III-Vcompounds for example, gallium phosphide, aluminum gallium phosphide, orother III-V combinations; also combinations of III, IV, V, or VImaterials, for example, silicon nitride, silicon oxide, aluminumcarbide, or aluminum oxide; also metallic silicides, germanides, andcarbides, for example, nickel silicide, cobalt silicide, tungstencarbide, or platinum germanium silicide; also doped variations includingphosphorus, arsenic, antimony, boron, or aluminum doped silicon orgermanium, carbon, or combinations like silicon germanium; also thesematerials with various crystal structures, including single crystalline,polycrystalline, nanocrystalline, or amorphous; also with combinationsof crystal structures, for instance with regions of single crystallineand polycrystalline structure (whether doped or undoped).

Moreover, the MEMS resonator array according to the present inventionsmay be formed in or on semiconductor on insulator (SOI) substrate usingwell-known lithographic, etching, deposition and/or doping techniques.For the sake of brevity, such fabrication techniques are not discussedherein. However, all techniques for forming or fabricating the resonatorstructure of the present invention, whether now known or laterdeveloped, are intended to fall within the scope off the presentinvention (for example, well-known formation, lithographic, etchingand/or deposition techniques using a standard or over-sized (“thick”)wafer (not illustrated) and/or bonding techniques (i.e., bonding twostandard wafers together where the lower/bottom wafer includes asacrificial layer (for example, silicon oxide) disposed thereon and theupper/top wafer is thereafter thinned (ground down or back) and polishedto receive the mechanical structures in or on).

Notably, the SOI substrate may include a first substrate layer (forexample, a semiconductor (such as silicon), glass or sapphire), a firstsacrificial/insulation layer (for example, silicon dioxide or siliconnitride) and a first semiconductor layer (for example, silicon, galliumarsenide or germanium) disposed on or above the sacrificial/insulationlayer. The mechanical structure maybe formed using well-knownlithographic, etching, deposition and/or doping techniques in or on thefirst semiconductor layer (for example, semiconductors such as silicon,germanium, silicon-germanium or gallium-arsenide).

In one embodiment, the SOI substrate may be a SIMOX wafer which isfabricated using well-known techniques. In another embodiment, the SOIsubstrate may be a conventional SOI wafer having a first semiconductorlayer. In this regard, SOI substrate, having a relatively thin firstsemiconductor layer, may be fabricated using a bulk silicon wafer whichis implanted and oxidized by oxygen to thereby form a relatively thinSiO₂ beneath or underneath the single or mono crystalline wafer surface.In this embodiment, the first semiconductor layer (i.e., monocrystallinesilicon) is disposed on the first sacrificial/insulation layer (i.e.silicon dioxide) which is disposed on a first substrate layer (i.e.,monocrystalline silicon in this example).

In those instances where the MEMS resonators of the MEMS resonator arrayare fabricated in or on polycrystalline silicon or monocrystallinesilicon, certain geometric shaped MEMS resonator structures according tothe present inventions, for example, the rounded square shapedresonator, may maintain structural and material symmetry withpolycrystalline silicon or monocrystalline silicon. In particular, arounded square shape MEMS resonator according to the present inventionsmay be inherently more compatible with the cubic structure ofmonocrystalline silicon. In each lateral orthogonal direction on astandard wafer (e.g. 100, 010, or 110), the properties of themonocrystalline silicon may be matched to one or more geometric shapedresonators. In this regard, the crystalline properties ofmonocrystalline silicon may have the same or suitable symmetry as theone or more geometric shaped resonator structure.

The MEMS resonator array 100 of the present invention may be packagedusing a variety of techniques and materials, for example, thin filmtechniques, substrate bonding techniques (for example, bondingsemiconductor or glass-like substrates) and prefabricated package (forexample, a TO-8 “can”). Indeed, any packaging and/or fabricatingtechniques may be employed, whether now known or later developed; assuch, all such fabrication and/or packaging techniques are intended tofall within the scope of the present invention. For example, thesystems, devices and/or techniques described and illustrated in thefollowing non-provisional patent applications may be implemented:

(1) “Electromechanical System having a Controlled Atmosphere, and Methodof Fabricating Same”, which was filed on Mar. 20, 2003 and assigned Ser.No. 10/392,528;

(2) “Microelectromechanical Systems, and Method of Encapsulating andFabricating Same”, which was filed on Jun. 4, 2003 and assigned Ser. No.10/454,867; and

(3) “Microelectromechanical Systems Having Trench Isolated Contacts, andMethods of Fabricating Same”, which was filed on Jun. 4, 2003 andassigned Ser. No. 10/455,555.

The inventions described and illustrated in the aforementioned patentapplications may be employed to fabricate MEMS resonators and the arrayof the present inventions. For the sake of brevity, those discussionswill not be repeated. It is expressly noted, however, that the entirecontents of the aforementioned patent applications, including, forexample, the features, attributes, alternatives, materials, techniquesand/or advantages of all of the inventions/embodiments, are incorporatedby reference herein.

Where MEMS resonator 102 implements a rounded square shape resonatorstructure that is symmetrically anchored (see, for example, FIG. 30B),the center of gravity of the structure remains relatively constant orfixed during operation. Notably, the four beam sections of MEMSresonator 102 implementing a rounded square shape resonator structuremay statistically average Gaussian process tolerances which may providebetter parameter control.

As mentioned above, MEMS resonator array 100 may employ any anchoringtechnique or anchor structure, whether now known or later developed. Inaddition, the stress/strain management techniques/structures (forexample, stress/strain mechanisms 120) may be implemented in conjunctionwith any of the anchoring technique or anchor structure described andillustrated herein and/or, whether now known or later developed. Forexample, the substrate anchors and/or stress/strain managementtechniques/structures may be placed at one, some or all of nodal pointsand/or anchors of one or more of the MEMS resonators 102. Othersubstrate anchoring-stress/strain management techniques may also besuitable. (See, for example, FIGS. 44-48). Indeed, MEMS resonator 102may be coupled to a substrate anchor (and stress/strain mechanism 120)at non-nodal points in a symmetrical or non-symmetrical manner (forexample, in or around a “center” of MEMS resonator 102). Notably, theanchoring-stress/strain management techniques may be implemented inconjunction with any of the embodiments described and illustratedherein. (See, for example, FIGS. 49-52).

Further, the loading relief techniques/structures (for example, loadingrelief mechanisms 12) may also be implemented in conjunction with any ofthe embodiments described and illustrated herein. (See, for example,FIGS. 52-55).

In the claims, the term “straight elongated beam section” means (i) astraight or substantially straight elongated beam, and/or (ii) anelongated beam having a longitudinal axis that is straight orsubstantially straight regardless of variations in thickness and/orwidth (if any) of the beam, and/or (iii) a beam that is substantiallymore straight than curved.

Further, in the claims, the term “slots” means openings, voids and/orslots (whether extending partially or entirely through the entireheight/thickness of the elongated beam section or curved section), ofany shape and/or size. Moreover, in the claims, the term “voids” meansopenings, voids and/or slots (whether extending partially or entirelythrough the entire height/thickness of the resonator coupling section),of any shape and/or size.

The above embodiments of the present inventions of MEMS resonator array100 are merely exemplary. They are not intended to be exhaustive or tolimit the inventions to the precise forms, techniques, materials and/orconfigurations disclosed. Many modifications and variations are possiblein light of the above teaching. It is to be understood that otherembodiments may be utilized and operational changes may be made withoutdeparting from the scope of the present invention. As such, theforegoing description of the exemplary embodiments of the invention hasbeen presented for the purposes of illustration and description. Manymodifications and variations are possible in light of the aboveteaching. It is intended that the scope of the invention not be limitedsolely to this detailed description.

In another aspect, the present invention is a plurality of square frameresonators arranged in an N×M MEMS frame array structure (where N and Mare integers). Each beam section of the individual square shaped MEMSresonator is shared with an adjacent resonator. In this way, thestructure provides different and resonant coupling effects. In addition,the structure provides a relatively low energy loss, high Q-factor andflexibility of driving/sensing electrode placement.

With reference to FIGS. 56A and 56B, N×M MEMS frame array structure 200(in this exemplary embodiment, where N and M are equal to 2) includessquare shaped MEMS resonators 202 a-d. The square shaped MEMS resonators202 a-d each includes four beam sections 204. Two of the beam sections204 of each square shaped MEMS resonators 202 a-d are shared withadjacent square shaped MEMS resonators 202 a-d. For example, squareshaped MEMS resonator 202 a shares (i) beam section 204 c with squareshaped MEMS resonator 202 b and (ii) beam section 204 d with squareshaped MEMS resonator 202 d. Similarly, square shaped MEMS resonator 202c shares (i) beam section 204 b with square shaped MEMS resonator 202 band (ii) beam section 204 a with square shaped MEMS resonator 202 d. Inthis way, each square shaped MEMS resonators 202 a-d is mechanicallycoupled to and/or integrated with the other square shaped MEMSresonators 202 a-d. In operation, square shaped MEMS resonators 202 a-dvibrate in-plane and at the same frequency because of the mechaniccoupling.

The MEMS frame array structure may be anchored using a number oftechniques, including those described above with respect to MEMS framearray structure. Where the corner sections of one or more square shapedMEMS resonators include nodal points, it may be advantageous to anchorMEMS frame array structure to the substrate at the nodal points. In thisregard, with reference to FIGS. 57A and 57B, in one embodiment, MEMSframe array structure 200 includes anchor coupling sections 206 thatmechanically couple MEMS frame array structure 200 to anchors 208. Theanchor coupling sections 206 are connected to MEMS frame array structure200 at or near nodal points 210. In this way, the vertical andhorizontal energy losses due to anchoring will be minimized, reducedand/or limited, which may result or provide a relatively high Q MEMSstructure.

Notably, the anchoring technique illustrated in FIGS. 57A and 577B,further provides the benefit whereby no additional or extra mask isnecessary for defining the anchor to the substrate. That is, squareshaped MEMS resonators 202 a-d and the anchoring structure may befabricated

contemporaneously. The MEMS frame array structure 200 need not beanchored at every nodal point or area but may be anchored at one or morelocations, preferably at one or more nodal locations (areas or locationsof the resonator that do not move, experience little movement, and/orare substantially stationary when the resonator oscillates). Forexample, with reference to FIGS. 57A, 58 and 59, MEMS frame arraystructure 200, may be anchored at one point, two points and/or fourareas or portions of MEMS frame array structure 200 (preferably, forexample, at or near nodal points 210 of one or more square shaped MEMSresonators 202 a-d). In this regard, one or more anchor couplingsections 206 connect(s) certain comers formed by beam sections 204 tocorresponding anchors 208.

Notably, with reference to FIGS. 60A and 60B, MEMS frame array structure200 of the present inventions may employ stress/strain relief mechanisms212 (for example, springs or spring-like components) to manage, control,reduce, eliminate and/or minimize any stress or strain on the substrateat the location of the anchor 208 which is caused by the motion of one,some or all of points at which MEMS frame array structure 200 isanchored through or at the substrate. For example, the corner of squareshaped MEMS resonators 202 a is mechanically coupled to stress/strainrelief mechanism 212 via anchor coupling section 206.

Notably, in addition to or in lieu thereof, MEMS frame array structure200 may be anchored to the substrate via one or more of the internalcorners of square shaped MEMS resonators 202 (see, for example, nodalpoints 210 c in FIGS. 60A and 60B). In this regard, the anchor may belocated under one, some or all of the internal corners of square shapedMEMS resonators 202 since all those corners may be designed to includemotionless nodes. Where MEMS frame array structure 200 includes a largenumber of square shaped MEMS resonators 202, in order to enhancehorizontal plane (in-plane) vibration of MEMS frame array structure 200,it may be advantageous to employ one or more anchor structures in or atinternal corners of square shaped MEMS resonators 202.

In operation, each of square shaped MEMS resonators 202 of MEMS framearray structure 200 vibrate in-plane and at the same frequency. Thephase difference of any two adjacent square shaped MEMS resonators 202is or is approximately 180 degrees. In this regard, with reference toFIGS. 61 and 62, in one embodiment, when induced square shaped MEMSresonators 202 vibrate approximately 180 degrees out-of-phase relativeto adjacent square shaped MEMS resonators 202. For example, squareshaped MEMS resonators 202 a vibrates approximately 180 degrees out-1of-phase relative to square shaped MEMS resonators 202 b and 202 e. Thevibration modes of square shaped MEMS resonators 202 may be theconventional flexural in place modes. As such, it is not necessary toplace any sense or drive electrodes “underneath” or “above” squareshaped MEMS resonators 202 in order to drive and sense MEMS frame arraystructure 200.

Notably, with continued reference to FIG. 62, nodal points 210 in or onthe corners of square shaped MEMS resonators 202 experience little to nomovement during operation. That is, as square shaped MEMS resonators 202oscillate between the first deflected state and the second deflectedstate, the areas or portions of the corners, particularly those that areconnect to anchor coupling sections 210, are relatively stationary.

With reference to FIGS. 63 and 64, in operation, the exterior cornersections of square shaped MEMS resonators 202 a and 202 c are relativelymotionless and stress-free nodes (i.e., nodal points). As such, in thisembodiment, MEMS frame array structure 200 includes anchor couplingsections 206 that mechanically couple MEMS frame array structure 200 toanchors 208 thereby minimizing, reducing and/or limiting the verticaland horizontal energy losses due, for example, motional resistance at ananchoring point.

The sense and drive electrodes and circuitry may be configured toprovide a single-ended output signal or differential output signals. Forexample, With reference to FIG. 65, in one embodiment, MEMS frame arraystructure 200 is configured to provide a differential output signal. Inthis embodiment, the sense and drive electrodes and circuitry areconfigured to provide output signals that are (or are substantially) 180degrees out of phase. In this way, MEMS frame array structure 200provides a differential output signal pair which includes a relativelylarge signal to noise relationship due to the summing effects ofoscillating beam sections 204 (for example, symmetrical oscillating beamsections) of the plurality of square shaped MEMS resonators 202.

The differential drive circuitry 222 and differential sense circuitry224 may be conventional well-known circuitry. Indeed, differential drivecircuitry 222 and differential sense circuitry 224 may be any type ofcircuitry (whether or not integrated (or fabricated) on the samesubstrate in which the MEMS frame array structure 200 resides), and allsuch circuitry, whether now known or later developed, are intended tofall within the scope of the present invention.

In addition, drive electrodes 214 and 216, and sense electrodes 218 and220, may be of a conventional, well known type or may be any type and/orshaped electrode whether now known or later developed. Further, thephysical electrode mechanisms may include, for example, capacitive,piezoresistive, piezoelectric, inductive, magnetorestrictive andthermal. Indeed, all physical electrode mechanisms whether now known orlater developed are intended to fall within the scope of the presentinvention.

The drive electrodes 214/216 and sense electrodes 218/220 may bedisposed or positioned relative to beam sections of square shaped MEMSresonators 202 in order to detect one or more selected or predeterminedharmonics of beam sections. Moreover, the number and length of driveelectrodes 214/216 and sense electrodes 218/220 may be selected in orderto optimize, enhance and/or improve the operation of the MEMS resonator.Further, drive electrodes 214/216 and sense electrodes 218/220 may befabricated without an additional or extra mask(s). That is, squareshaped MEMS resonators 202 a-d, drive electrodes 214/216 and senseelectrodes 218/220 maybe fabricated contemporaneously.

The differential drive circuitry 222 and differential sense circuitry224 may be integrated on the same substrate in which MEMS frame arraystructure 200 resides (or is fabricated in). In addition thereto, or inlieu thereof, differential drive circuitry 222 and differential sensecircuitry 224 may be integrated on a substrate that is physicallyseparate from (and electrically interconnected with) the substrate inwhich the MEMS resonator structure resides.

It should be noted that there are many other configurations and/orarchitectures of the sense and drive electrodes that cause or inducebeam 204 to resonate and thereby generate and/or produce output signalsthat are (or are substantially) 180 degrees out of phase. All suchconfigurations and/or architectures are intended to fall within thescope of the present invention.

The MEMS frame array structure of the present inventions may befabricated from well-known materials using well-known techniques. Forexample, the MEMS frame array structure (including its constituentparts) may be fabricated from well-known semiconductors such as silicon,germanium, silicon-germanium or gallium-arsenide. Indeed, the MEMS framearray structure may be comprised of, for example, materials in column IVof the periodic table, for example silicon, germanium, carbon; alsocombinations of these, for example, silicon germanium, or siliconcarbide; also of III-V compounds for example, gallium phosphide,aluminum gallium phosphide, or other III-V combinations; alsocombinations of III, IV, V, or VI materials, for example, siliconnitride, silicon oxide, aluminum carbide, or aluminum oxide; alsometallic silicides, germanides, and carbides, for example, nickelsilicide, cobalt silicide, tungsten carbide, or platinum germaniumsilicide; also doped variations including phosphorus, arsenic, antimony,boron, or aluminum doped silicon or germanium, carbon, or combinationslike silicon germanium; also these materials with various crystalstructures, including single crystalline, polycrystalline,nanocrystalline, or amorphous; also with combinations of crystalstructures, for instance with regions of single crystalline andpolycrystalline structure (whether doped or undoped).

Moreover, the MEMS frame array structure according to the presentinventions may be formed in or on semiconductor on insulator (SOI)substrate using well-known lithographic, etching, deposition and/ordoping techniques. For the sake of brevity, such fabrication techniquesare not discussed herein. However, all techniques for forming orfabricating the resonator structure of the present invention, whethernow known or later developed, are intended to fall within the scope ofthe present invention (for example, well-known formation, lithographic,etching and/or deposition techniques using a standard or over-sized(“thick”) wafer (not illustrated) and/or bonding techniques (i.e.,bonding two standard wafers together where the lower/bottom waferincludes a sacrificial layer (for example, silicon oxide) disposedthereon and the upper/top wafer is thereafter thinned (ground down orback) and polished to receive the mechanical structures in or on).

Notably, the SOI substrate may include a first substrate layer (forexample, a semiconductor (such as silicon), glass or sapphire), a firstsacrificial/insulation layer (for example, silicon dioxide or siliconnitride) and a first semiconductor layer (for example, silicon, galliumarsenide or germanium) disposed on or above the sacrificial/insulationlayer. The mechanical structure maybe formed using well-knownlithographic, etching, deposition and/or doping techniques in or on thefirst semiconductor layer (for example, semiconductors such as silicon,germanium, silicon-germanium or gallium-arsenide).

In one embodiment, the SOI substrate may be a SIMOX wafer which isfabricated using well-known techniques. In another embodiment, the SOIsubstrate maybe a conventional SOI wafer having a first semiconductorlayer. In this regard, SOI substrate, having a relatively thin firstsemiconductor layer, may be fabricated using a bulk silicon wafer whichis implanted and oxidized by oxygen to thereby form a relatively thinSiO₂ beneath or underneath the single or mono crystalline wafer surface.In this embodiment, the first semiconductor layer (i.e., monocrystallinesilicon) is disposed on the first sacrificial/insulation layer (i.e.silicon dioxide) which is disposed on a first substrate layer (i.e.,monocrystalline silicon in this example).

In those instances where the plurality of square shaped MEMS resonatorsof the MEMS frame array structure are fabricated in or onpolycrystalline silicon or monocrystalline silicon, certain geometricshaped MEMS resonator structures according to the present inventions,for example, the rounded square shaped MEMS resonator, may maintainstructural and material symmetry with polycrystalline silicon ormonocrystalline silicon. In particular, a rounded square shape MEMSresonator according to the present inventions may be inherently morecompatible with the cubic structure of monocrystalline silicon. In eachlateral orthogonal direction on a standard wafer (e.g. 100, 010, or110), the properties of the monocrystalline silicon may be matched toone or more geometric shaped resonators. In this regard, the crystallineproperties of monocrystalline silicon may have the same or suitablesymmetry as the one or more geometric shaped resonator structure.

The MEMS frame array structure of the present invention maybe packagedusing a variety of techniques and materials, for example, thin filmtechniques, substrate bonding techniques (for example, bondingsemiconductor or glass-like substrates) and prefabricated package (forexample, a TO-8 “can”). Indeed, any packaging and/or fabricatingtechniques may be employed, whether now known or later developed; assuch, all such fabrication and/or packaging techniques are intended tofall within the scope of the present invention. For example, thesystems, devices and/or techniques described and illustrated in thefollowing non-provisional patent applications may be implemented:

(1) “Electromechanical System having a Controlled Atmosphere, and Methodof Fabricating Same”, which was filed on Mar. 20, 2003 and assigned Ser.No. 10/392,528;

(2) “Microelectromechanical Systems, and Method of Encapsulating andFabricating Same”, which was filed on Jun. 4, 2003 and assigned Ser. No.10/454,867; and

(3) “Microelectromechanical Systems Having Trench Isolated Contacts, andMethods of Fabricating Same”, which was filed on Jun. 4, 2003 andassigned Ser. No. 10/455,555.

The inventions described and illustrated in the aforementioned patentapplications may be employed to fabricate square shaped MEMS resonatorsand the MEMS frame array structure of the present inventions. For thesake of brevity, those discussions will not be repeated. It is expresslynoted, however, that the entire contents of the aforementioned patentapplications, including, for example, the features, attributes,alternatives, materials, techniques and/or advantages of all of theinventions/embodiments, are incorporated by reference herein.

Notably, the dimensions, characteristics and/or parameters of the squareshaped MEMS resonator and the MEMS frame array structure according tothe present inventions may be determined using a variety of techniquesincluding finite element modeling and simulation techniques (forexample, a finite element modeling via a computer driven analysis enginesuch as FemLab (from Consol), ANSYS (from ANSYS INC.), IDEAS and/orABAKUS and/or empirical data/measurements. For example, a finite elementmodeling engine, using or based on a set of boundary conditions (forexample, the size of the resonator structure), may be employed todesign, determine and/or assess the dimensions, characteristics and/orparameters of (i) beam sections 204, (ii) anchor coupling section 206(ii) nodal point(s) 210 (if any), and/or (vi) stress/strain mechanisms212. Indeed, the impact and/or response of square shaped MEMS resonator202, alone or incorporated into MEMS frame array structure 200, on or atthe anchor and/or substrates may also be observed and/or determinedusing such a finite element modeling, simulation and analysis engine.

The above embodiments of the present inventions of MEMS frame arraystructure 200 are merely exemplary. They are not intended to beexhaustive or to limit the inventions to the precise forms, techniques,materials and/or configurations disclosed. Many modifications andvariations are possible in light of the above teaching. It is to beunderstood that other embodiments maybe utilized and operational changesmay be made without departing from the scope of the present invention.As such, the foregoing description of the exemplary embodiments of theinvention has been presented for the purposes of illustration anddescription. Many modifications and variations are possible in light ofthe above teaching. It is intended that the scope of the invention notbe limited solely to this detailed description.

The MEMS array structure and MEMS frame array structure of the presentinvention may be implemented in a wide variety of applicationsincluding, for example, timing or clock devices or clock alignmentcircuitry wherein a resonator or oscillator is employed. Indeed, MEMSarray structure and MEMS frame array structure of the present inventionmay be implemented in any system or device where a clock signal orreference clock is employed, for example, in data, satellite and/orwireless communication systems/networks, mobile phone systems/networks,Bluetooth systems/networks, zig bee systems/networks, watches, real timeclocks, set top boxes and systems/networks therefor, computer systems(for example, laptops, PCs and/or handheld devices), televisions andsystems/networks therefor, consumer electronics (such as DVDplayer/recorder, MP3, MP2, DIVX or similar audio/video systems).

1. A MEMS array structure, comprising: a plurality of MEMS resonatorsforming an array, each MEMS resonator including a plurality of beamsections, wherein at least one of the beam sections is a shared beamsection that is also included in another of the plurality of MEMSresonators which is adjacent to the respective MEMS resonator.
 2. TheMEMS array structure of claim 1, wherein each MEMS resonator includes atleast two shared beam sections.
 3. The MEMS array structure of claim 1,wherein each MEMS resonator is square shaped and includes four beamsections.
 4. The MEMS array structure of claim 3, where the shared beammechanically couples the respective MEMS resonator to its adjacent MEMSresonator, the mechanical couplings of array causing the all of theplurality of MEMS resonators to vibrate in-plane and at a same frequencyduring operation of the array.
 5. The MEMS array structure of claim 3,further comprising: a substrate, wherein at least one corner section ofat least one of the plurality of MEMS resonators includes acorresponding nodal point at which the array is anchored to thesubstrate.
 6. The MEMS array structure of claim 5, further comprising:an anchor configured to anchor the array to the substrate; and an anchorcoupling section connected one of at and near a corresponding one of theat least one nodal point and mechanically coupling the array to theanchor.
 7. The MEMS array structure of claim 6, wherein the structureincludes fewer anchors than nodal points.
 8. The MEMS array structure ofclaim 6, further comprising: a relief mechanism arranged to manage oneof stress and strain on the substrate at a location of the anchor. 9.The MEMS array structure of claim 8, wherein the relief mechanism is aspring.
 10. The MEMS array structure of claim 8, wherein the reliefmechanism is disposed within the anchor coupling section and between theanchor and the corresponding one of the at least one nodal point. 11.The MEMS array structure of claim 6, wherein the corresponding one ofthe at least one nodal point is of an external corner section of thearray.
 12. The MEMS array structure of claim 5, further comprising: ananchor located under a corresponding one of the at least one nodal pointand configured to anchor the array to the substrate, wherein thecorresponding one of the at least one nodal point is of an internalcorner section of the array.
 13. The MEMS array structure of claim 1,wherein the plurality of MEMS resonators are arranged so that, duringoperation, any two adjacent ones of the plurality of MEMS resonatorsvibrate 180 degrees out-of-phase relative to each other.
 14. The MEMSarray structure of claim 1, further including: at least one senseelectrode; at least one drive electrode; sense circuitry coupled to theat least one sense electrode; and drive circuitry coupled to the atleast one drive electrode; wherein the at least one sense electrode andat least one drive electrode are located one of underneath and above thearray.
 15. The MEMS array structure of claim 14, wherein the at leastone sense electrode provides at least one signal to the sense circuitrywhich, in response, provides a differential output signal.
 16. The MEMSarray structure of claim 14, wherein the at least one sense electrodeprovides at least one signal to the sense circuitry which, in response,provides a single ended output signal.
 17. The MEMS array structure ofclaim 14, wherein the at least one sense electrode, the at least onedrive electrode, the sense circuitry, and the drive circuitry provideoutput signals that are 180 degrees out-of-phase.
 18. The MEMS arraystructure of claim 14, wherein the at least one drive electrode inducesthe plurality of beam sections to resonate.
 19. The MEMS array structureof claim 14, wherein the at least one sense electrode and the at leastone drive electrode are positioned relative to the plurality of beamsections so that at least one harmonic of the plurality of beam sectionsis detected.